Spring mechanisms for providing predetermined compression values in track-type tractors, vehicle disc brakes, railway trucks and the like are well known. Such mechanisms must provide sufficient resistance to compression for their intended purposes yet must be sufficiently resilient to recoil under heavy shock loads without failure. It is desirable that such spring mechanisms be capable of field assembly and removal.
Typical spring assemblies include one or more (usually two) concentric coil springs retained between two abutment collars or end caps. The collars or caps are connected by a bolt or similar retention device. In certain applications, one of the end caps may be fixed and the other movable to allow spring compression. Often, both end caps are movable.
The amount of compression of the springs and, therefore, the force required to further compress the mechanism may be predetermined by selecting a retention bolt of appropriate length. Such bolts are usually of unitary construction, and are secured to the retaining caps by any of a variety of means, including receipt in a threaded bore in the cap, or by retention against the cap by a flange or head on the bolt. Such a flange may be provided by a nut receiving an end of the bolt.
Spring assemblies of the prior art have several disadvantages, including a tendency to fly apart when being handled, disassembled, assembled, or removed from a mechanism. For example, a retaining nut might be loosened from a bolt, thereby allowing the spring to drive the retaining caps apart. Such disassembly, whether intentional or inadvertent, is to be avoided due to the resultant rapid release of spring forces.
Further, previous spring assemblies are not susceptible to easy assembly, due to the great forces and precision required in determining the compressed length of the springs.